According to conventional methods for operating an internal combustion engine, a setpoint value for a variable characterizing the air/fuel mixture is specified in at least one operating state of the internal combustion engine.
In particular, this is the case in Lambda control in which an actual value for an oxygen concentration in the exhaust gas, which characterizes the air/fuel mixture in the combustion chamber, i.e., an actual Lambda value, is adapted to a setpoint Lambda value as a setpoint value for the oxygen concentration in the exhaust gas characterizing the air/fuel mixture.
Furthermore, German Published Patent Application No. 44 15 994 describes a control system for an internal combustion engine, which enriches the air/fuel mixture supplied to the internal combustion engine if a threshold value of a signal that indirectly or directly indicates the efficiency of the internal combustion engine is not attained. The enriching prevents that the exhaust gas temperature, which increases as the efficiency of the internal combustion engine decreases, assumes values that become so high that damage occurs to the discharge valves or the exhaust gas system, in particular the exhaust-gas catalyst.